Point 11 of my 11 point list of methods for reducing
cracking in

portland cement stucco

Point eleven - The
big one. Acrylic additives

This is the big one The greatest crack preventing discovery
we have made is the use of acrylic additives in the finish coat.

There are
several types and brands available. The major use
of acrylic admixtures has been in swimming pools, as a method of
bonding
portland cement mortar to concrete. Acrylics have been also used for
bonding
cement plaster to cast in place concrete, and other substrates that are
normally too slick, too porous, or not porous enough for a permanent
bond.

I started using acrylics in the finish coat in searching for a
method
to retain the color in mix. Pre-mixed color stucco finishes from
California
have a small quantity of plastic chemical to retain the color in the
mix.

Using acrylics with color not only improved color retention,
but I discovered our jobs had no cracks, or at least very few. There
also were no check
cracks or imperfections from shrinkage, because of the slower final set
of the mortar.

Other benefits of acrylics: Increased bonding strength (of
course, they
are bonding admixtures):

Improved compression strength.

Few to no cracks due to
flexibility.

No need to wet the wall before
applying the finish coat, which causes
loss of
color.

Reduced porousness, reducing
water infiltration, and spalling.

Reduced likelihood of
efflorescence.

The increased
material cost is about 50 cents a square foot, but the
the overall quality of the finish product is vastly superior, so I have
no problem charging more for my jobs.